Compositions for making ene-thiol elastomers

ABSTRACT

In one aspect, the invention provides ene-thiol elastomers comprising the reaction product of a polythiol free of hydrophilic groups and having at least two thiol groups and an aromatic, heterocyclic, aliphatic, or cycloaliphatic polyene having at least two reactive unsaturated carbon to carbon bonds. In another aspect, the invention provides ene-thiol elastomer comprising the reaction product of (a) a thiol terminated oligomer comprising the reaction product of a polythiol having two thiol groups and a first polyene or mixture of polyenes having two reactive unsaturated carbon to carbon bonds; and (b) a second polyene or a mixture of polyenes having at least 5 percent functional equivalents of unsaturated carbon to carbon bonds from polyenes having at least three unsaturated carbon to carbon bonds. The ene-thiol elastomers of the invention have a weight increase of not more than 4 weight percent in 15 days at a temperature of 22° C. when immersed in a solution of 96 parts by weight water and 4 parts by weight n-butanol and/or a water vapor transmission rate of less than 50 g-mm/m 2 -day at 40° C. according to ASTM D814.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.09/567,944, filed May 10, 2000, now U.S. Pat. No. 6,479,622, nowallowed, which claims the benefit of U.S. Provisional Application No.60/134,012, filed May 10, 1999.

FIELD OF THE INVENTION

The invention relates to curable compositions used for making ene-thiolelastomers and cured ene-thiol elastomers made therefrom.

BACKGROUND OF THE INVENTION

Electronic circuits must be protected from exposure to harsh corrosiveenvironments to maintain the performance of the electronic device. Manyelectronic circuits are used in environments where they are exposed tocorrosive liquids. For example, adhesives and encapsulants used toassemble ink jet cartridges must protect the flexible circuit thatcontrols the ink jet head from exposure to corrosive inks. Theseadhesives and encapsulants experience long term exposure to verycorrosive inks. If the adhesive or encapsulant degrade or excessivelyswell, the ink contacts and corrodes the circuit.

Thermosetting resins, frequently epoxy resins, are used to protectcircuits from corrosive environments. Epoxy resins have severalcharacteristics that limit their ability to perform well. Traces ofchloride ion, which are frequently present in epoxy resins, promote thecorrosion of circuits. Epoxy networks are somewhat hydrophilic and swellin aqueous environments because of the secondary alcohols produced inthe curing reaction. Epoxy networks are frequently difficult to fullycure in the time/temperature constraints of electronic manufacturingprocesses. Unreacted epoxy groups are prone to hydrolysis, formingglycols, which further decreases the water resistance of the network.These epoxy characteristics limit their use as adhesives andencapsulants in corrosive environments.

Many combinations of polyfunctional olefins and mercaptans have beenused to prepare ene-thiol networks. While many monomers have veryattractive process characteristics (low viscosity and rapid UV curing),they do not provide networks having the requisite environmentalresistance to withstand highly corrosive aqueous environments. Polyetherdimercaptans are frequently used in ene-thiol compositions. Thesemonomers introduce hydrophilic units to the cured network, resulting inexcessive swelling in aqueous environments. Multifunctionalmercaptoacetates and propionates are other commonly used thiol monomers.In addition to their hydrophilic character, the ester linkage introducesa site for hydrolysis and network degradation.

SUMMARY OF THE INVENTION

In one aspect, the invention provides a curable composition for makingan ene-thiol elastomer comprising a mixture of a polythiol, or a mixtureof polythiols, having at least two thiol groups and free of hydrophilicgroups, and an aromatic, heterocyclic, aliphatic, or cycloaliphaticpolyene having at least two reactive unsaturated carbon to carbon bonds,wherein the composition in cured form, when immersed in a solution of 96parts by weight water and 4 parts by weight n-butanol, shows a weightincrease of not more than 4 weight percent, preferably, not more than 3weight percent, and more preferably, not more than 2.5 weight percent in15 days at a temperature of 22° C.

In another aspect, the invention provides a ene-thiol elastomercomprising the reaction product of a composition comprising a mixture ofa polythiol having at least two thiol groups and free of hydrophilicgroups and an aromatic, heterocyclic, aliphatic, or cycloaliphaticpolyene having at least two reactive unsaturated carbon to carbon bonds,wherein the ene-thiol elastomer, when immersed in a solution of 96 partsby weight water and 4 parts by weight butyl alcohol, shows a weightincrease of not more than 4 weight percent, preferably, not more than 3weight percent, and more preferably, not more than 2.5 weight percent in15 days at a temperature of 22° C.

In another aspect, the invention provides a curable composition formaking an ene-thiol elastomer comprising a mixture of (a) a thiolterminated oligomer comprising the reaction product of a polythiolhaving two thiol groups and a first polyene or mixture of polyeneshaving two reactive unsaturated carbon to carbon bonds, and (b) a secondpolyene or a mixture of polyenes having at least 5 percent functionalequivalents of unsaturated carbon to carbon bonds from polyenes havingat least three unsaturated carbon to carbon bonds, wherein thecomposition in cured form, when immersed in a solution of 96 parts byweight water and 4 parts by weight n-butanol, shows a weight increase ofnot more than 4 weight percent, preferably, not more than 3 weightpercent, and more preferably, not more than 2.5 weight percent in 15days at a temperature of 22° C.

Generally, not more than 50 weight percent, preferably, not more than 30weight percent, more preferably, not more than 20 weight percent, andeven more preferably, none of the polythiol used to make the oligomerhas hydrophilic groups. The first and second polyenes or mixtures ofpolyenes may be the same or different. Preferred first polyenes includedivinyl ethers, and cyclic polyenes. Preferred polythiols includedimercaptodiethyl sulfide, 1,6-hexanedithiol, and1,8-dimercapto-3,6-dithiaoctane.

In another aspect, the invention provides a ene-thiol elastomercomprising the reaction product of a composition comprising the reactionproduct of (a) a thiol terminated oligomer comprising the reactionproduct of a polythiol having two thiol groups and a first polyene ormixture of polyenes having two reactive unsaturated carbon to carbonbonds and (b) a second polyene or a mixture of polyenes having at least5 percent functional equivalents of unsaturated carbon to carbon bondsfrom polyenes having at least three unsaturated carbon to carbon bonds,wherein the composition in cured form, when immersed in a solution of 96parts by weight water and 4 parts by weight n-butanol, shows a weightincrease of not more than 4 weight percent, preferably, not more than 3weight percent, and more preferably, not more than 2.5 weight percent in15 days at a temperature of 22° C.

Generally, not more than 50 weight percent, preferably, not more than 30weight percent, more preferably, not more than 20 weight percent, andeven more preferably, none of the polythiol used to make the oligomerhas hydrophilic groups. The first and second polyenes or mixtures ofpolyenes may be the same or different. Preferred first polyenes includedivinyl ethers, and cyclic polyenes. Preferred polythiols includedimercaptodiethyl sulfide, 1,6-hexanedithiol, and1,8-dimercapto-3,6-dithiaoctane.

In another aspect, the invention provides ene-thiol elastomerscomprising the reaction product of a composition comprising a mixture ofa polythiol having at least two thiol groups and free of hydrophilicgroups and an aromatic, heterocyclic, aliphatic, or cycloaliphaticpolyene having at least two reactive unsaturated carbon to carbon bonds,wherein the ene-thiol elastomers have a water vapor transmission rate ofless than 50, preferably less than 30, more preferably, less than 20g-mm/m²-day at 40° C. according to ASTM D814.

In another aspect, the invention provides ene-thiol elastomerscomprising the reaction product of a composition comprising the reactionproduct of (a) a thiol terminated oligomer comprising the reactionproduct of a polythiol having two thiol groups and a first polyene ormixture of polyenes having two reactive unsaturated carbon to carbonbonds and (b) a second polyene or a mixture of polyenes having at least5 percent functional equivalents of unsaturated carbon to carbon bondsfrom polyenes having at least three unsaturated carbon to carbon bonds,wherein the ene-thiol elastomers have a water vapor transmission rate ofless than 50, preferably less than 30, more preferably, less than 20g-mm/m²-day at 40° C. according to ASTM D814.

In another aspect, the invention provides an ene-thiol elastomercomprising the reaction product of (a) an unsaturated carbon to carbonbond terminated oligomer comprising the reaction product of a firstpolythiol having two thiol groups and a polyene or mixture of polyeneshaving two reactive unsaturated carbon to carbon bonds; and (b) a secondpolythiol or mixture of polythiols having at least 5 percent functionalthiol equivalents from polythiols having at least three thiol groups,wherein the ene-thiol elastomer shows a weight increase of not more than4 weight percent in 15 days at a temperature of 22° C. when immersed ina solution of 96 parts by weight water and 4 parts by weight n-butanol.

In other aspects, the invention provides a method of making the aboveene-thiol elastomers, and an article of manufacture comprisingelectrical or electronic components encapsulated in a ene-thiolelastomer of the invention.

The compositions of the invention preferably contain a free radicalinitiator and more preferably, a photoinitiator.

As used herein, the term “polythiols” refers to simple or complexorganic compounds which are substantially free of disulfide linkages andhave a multiplicity of pendant or terminally positioned -SH functionalgroups per molecule.

As used herein, the term “free of hydrophilic groups” when used todescribe polythiols means polythiols devoid of any ether, ester,hydroxyl, carbonyl, carboxylic acid, sulfonic acid linkages or groupswithin or pendant from the polythiol molecule.

As used herein, the term “polyene” refers to simple or complex speciesof alkenes having at least two reactive unsaturated carbon to carbonbonds per molecule.

As used herein, the terms “di functional”, “trifunctional”, and“tetrafunctional” when used to describe polythiols and polyenes meanspolythiols having two, three, and four thiol groups and polyenes havingtwo, three, and four reactive unsaturated carbon to carbon bonds.

The compositions of the invention are generally low viscosity liquidsthat can be uniformly coated onto flexible circuitry and rapidly curedby actinic radiation. The resulting ene-thiol elastomers are tough,flexible, and resist swelling or chemical degradation by water andcorrosive components of inks.

One of the unique properties of the ene-thiol elastomers of theinvention is the combination of flexibility with resistance to swellingand degradation by water and corrosive environments. Brittle thermosetresins, such as conventional epoxies, may provide reasonable resistanceto swelling by corrosive components of inks but are prone to crackingwhen used on a flexible circuit. The resulting cracks then provide apath for the corrosive liquid to penetrate the coating and corrode thesubstrate. Low Tg epoxies, acrylates, urethanes or other elastomericthermosetting resins, which are flexible and resist cracking, aregenerally prone to degradation by these corrosive liquids. The ene-thiolelastomers of the invention provide the swelling resistance of brittleglassy epoxy resins with elastomeric flexibility.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polythiols of the invention have at least two thiol groups and arefree of hydrophilic groups. Useful polythiols are also substantiallyfree of disulfide linkages that would impart chemical and/or thermalinstability to the crosslinked or cured network. The polythiols may bealiphatic or aromatic and may be monomeric or polymeric. Usefulpolythiols have the formula:

where m=2-12, n=2-12, q=0-4, where m and n can be the same or different;or the formula H-S-R-S-H, where R=C₅-C₈ cycloaliphatic radical.

The use of di-, tri-, and tetra-functional polythiols is alsocontemplated in the present invention.

Specific examples of useful polythiols include dimercaptodiethylsulfide; 1,6-hexanedithiol; 1,8-dimercapto-3,6-dithiaoctane;propane-1,2,3-trithiol;1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane;tetrakis(7-mercapto-2,5-dithiaheptyl)methane; and trithiocyanuric acid.The polythiols may be used alone or in combination with one another.

When using polythiols having two thiol groups, useful polyenes of theinvention may be characterized by mixtures of those materials having atleast 5 percent functional equivalents of unsaturated carbon to carbonbonds contributed by polyenes having at least three unsaturated carbonto carbon bonds. Preferred polyenes are heterocyclic, aliphatic, orcycloaliphatic diene, allyl ether, allyl ester, vinyl ether, styryl,(meth)acryl, allyl or vinyl compounds having at least two or threereactive unsaturated carbon to carbon bonds per molecule. Mixtures ofpolyenes, each having two and three unsaturated carbon to carbon bondsrespectively, are preferred. Specific examples includetriallyl-1,3,5-triazine-2,4,6-trione; 2,4,6-triallyloxy-1,3,5-triazine;1,4-cyclohexanedimethanol divinyl ether; 4-vinyl-1-cyclohexene;1,5-cyclooctadiene; and diallyl phthalate. Combinations of usefulpolyenes may also be used in the compositions of the invention. Thepolythiols and polyenes are present in the compositions and elastomersof the invention in a stoichiometric amount.

The composition of the invention may contain a free radical initiator,preferably a UV active free radical initiator, to cure or crosslink thecomposition. Useful free radical initiators which are well known in theart and include the class of free radical initiators are commonlyreferred to as “photoinitiators.” A preferred commercially availablefree radical initiator, also a photoinitiator, is IRGACURE 651,available from Ciba Specialty Chemicals, Tarrytown, N.J. Alternatively,the compositions of the invention may also contain thermally activatedfree radical initiators.

The compositions of the invention are generally made by mixing astoichiometric amount of one or more polythiols and one or more polyenesin an appropriate vessel. In the case of reacting polythiols andpolyenes, each having two thiol and unsaturated carbon to carbon bondsrespectively, it may be preferable to first form an oligomer using asub-stoichiometric amount of polyene and then reacting the oligomer witha polyene having at least three unsaturated carbon to carbon bonds toform the crosslinked elastomer. If a photoiniator is used, thecomponents may be mixed in the absence of actinic radiation and thenstored in the dark for extended periods of time. If desired, thecompositions of the invention may contain conventional inhibitors toprevent spontaneous radical polymerization.

One of the advantages of first preparing an oligomer by reacting asub-stoichiometric amount of polyene having two unsaturated carbon tocarbon bonds with polythiol having two thiol groups is that theoligomer, having an increased molecular weight, may be vacuumdevolatilized so to substantially reduce the objectionable odorcharacteristics of polythiols. The resulting oligomers have very lowvapor pressures by virtue of their molecular weight and have littleodor, but may contain volatile sulfur containing compounds that causeobjectionable odor. The removal of such compounds results incompositions having low odor. Another advantage of first preparingoligomers is that such preparation allows the use of combinations ofpolyenes having different reactivities. For example, a polyene havingtwo unsaturated carbon to carbon bonds having low reactivity can be usedto prepare the oligomer and a mixture of polyenes having two and threeunsaturated carbon to carbon bonds having relatively high reactivity canbe used to react with the oligomer to form the elastomer.

Alternatively, the ene-thiol elastomers of the invention may be madeusing a polythiol having either three or four thiol groups per moleculeand a polyene oligomer terminated with unsaturated carbon to carbonbonds. Such polyene oligomers can be made from the reaction of a polyenehaving two unsaturated carbon to carbon bonds and a sub-stoichiometricamount of a polythiol having two thiol groups per molecule. Elastomerscan be made by reacting the polyene oligomer with polythiols, wherein atleast 5 percent of the functional equivalents of thiol is provided bypolythiols having at least three thiol groups per molecule.

The compositions can then be applied to the desired substrate, forexample, electrical connectors, or other electrical components and thelike, and exposed to electron beam radiation. If the compositioncontains a photoinitiator, the composition may be exposed to any form ofactinic radiation, such as visible light or UV radiation, but ispreferably exposed to UVA (320 to 390 nm) or UVV (395 to 445 nm)radiation. Generally, the amount of actinic radiation should besufficient to form a solid mass that is not sticky to the touch.Generally, the amount of energy required curing the compositions of theinvention ranges from about 0.4 to 20.0 J/cm².

Glossary

DMDS—Dimercaptodiethyl sulfide (Structure 1), HSC₂H₄SC₂H₄SH, CAS No.3570-55-6, available from Itochu Specialty Chemical Inc.

DMDO—1,8-dimercapto-3,6-dioxooctane, HSC₂H₄OC₂H₄OC₂H₄SH, CAS NO.14970-87-7, available from Itochu Specialty Chemical Inc.

EBMP—Ethylene bis(3-mercaptopropionate), HSC₂H₄COOC₂H₄OOCC₂H₄SH,7575-23-7, available from Evans Chemetics Division of HampshireChemicals.

CAPCURE® 3-800—Trifunctional mercaptan terminated liquid polymer,available from Henkel Corporation.

HDT—1,6-hexanedithiol, HSC₆H₁₂SH, CAS No. 1191-43-1, available fromAldrich Chemical Company.

IGRACURE 651—2,2-Dimethoxy-2-phenylacetophenone, C₆H₅COC(OCH₃)₂C₆H₅, CASNo. 24650-42-8, available from Ciba Specialty Chemicals.

TAIC—Triallyl-s-triazine-2,4,6(1H,3H,5H)-trione, (Structure 2), CAS No.1025-15-6, available from Aldrich Chemical Company.

TAC—Triallyloxy-1,3,5-triazine, (Structure 3), CAS No. 101-37-1,available from Aldrich Chemical Company.

Rapi-Cure CHVE—1,4-cyclohexanedimethanol divinyl ether (Structure 4),CAS No. 17351-75-6, available from International Specialty Products.

VCH—4-vinyl-1-cyclohexene (Structure 5), CAS No. 100-40-3, availablefrom Aldrich Chemical Company.

COD—1,5-cyclooctadiene (Structure 6), CAS No. 111-78-4, available fromAldrich Chemical Company.

DAP—diallyl phthalate (Structure 7), CAS No. 131-17-9, available fromAldrich Chemical Company.

PEGDE—poly(ethylene glycol) divinyl ether (Structure 8), CAS No.50856-26-3, available from Aldrich Chemical Company.

AIBN—2,2-azobisisobutronitrile, CAS No. 78-67-1, available from AldrichChemical Company. It is used as a thermal free radical initiator.

NPAL—tris(N-nitroso-N-phenylhydroxylamine)aluminum salt, CAS No.15305-07-4, available from First Chemical Corporation. It is used as aradical inhibitor.

Oligomer Preparation

A variety of oligomers with different backbone structures weresynthesized. DMDS was chosen as a monomer to minimize the amount ofether linkages in the backbone and maximize the number of thioetherlinkages. The oligomers were prepared by the addition of a dimercaptanto a diolefin under free radical conditions. The molecular weight of theoligomer was controlled by reaction stoichiometry. The reactions werecarried out either thermally or photochemically. Polymerizations carriedout with less reactive olefins such as VCH and COD were more successfulusing the photochemical method.

Thermal Procedure. A dimercaptan or mixture of dimercaptans was weighedinto a flask, AIBN was added, and the flask was heated to 65° C. Adiolefin was added dropwise to the dimercaptan solution at a rate tomaintain the temperature in the flask between 90-100° C. After theaddition, the oligomer was stirred for 4 hours, and the temperature wasmaintained at 75-80° C. The reaction product was checked by ¹H NMR and¹³C NMR to determine whether any olefin groups remained. If olefin wasstill present in the product mixture, additional AIBN was added and theoligomer was stirred at 75-80° C. for an additional 5 hours, when theamount of olefin remaining was determined to be less than 4 percent by¹H NMR. The oligomers in Table 1 were prepared using the thermalprocedure.

Alternative Thermal Procedure. The reaction was carried out as describedabove; however, 0.5 percent AIBN was dissolved into the diolefin, andthe resulting solution was added to the dimercaptan.

TABLE 1 Initiator Reaction Target DMDS CHVE DAP Wt. % Time M_(N)Oligomer 1 100.3 g 112.7  —  0.3% 4 hr 2800 Oligomer 2 30.37 g 25.45 — 0.5% 4 hr  830 Oligomer 3 24.57 g — 35.06 g  0.6% 9 hr 2800 Oligomer 425.20 g — 25.24 g 0.75% 9 hr  830

Photochemical Procedure. A dimercaptan, a diolefin, and 0.5 weightpercent IRGACURE 651 were weighed into a glass jar. The contents of thejar were shaken and were irradiated for 4 hours with two GTE 15 wattSylvania 350 nm black light bulbs having a power output of 1 mW/cm².Additional IRGACURE 651 was added, and the oligomer was heated to 80° C.The oligomer was irradiated again for several hours. The reaction wasconsidered complete when greater than 95 percent of the olefin groupshad reacted as judged by ¹H and ¹³C NMR. The oligomers in Table 2 weremade using the photochemical procedure.

TABLE 2 Total Exposure Target DMDS VCH COD Initiator Time M_(N) Oligomer5 39.83 g 25.41 g — 1.3% 16 hr 2800 Oligomer 6 30.02 g 15.17 g — 0.5%  4hr  830 Oligomer 7 35.03 g — 22.33 g 1.0% 12 hr 2800 Oligomer 8 40.25 g— 21.53 g 1.2% 12 hr 1000

Oligomers 9 and 10 are described in Table 3 and contain a combination ofVCH, which contains no oxygen ether linkages, and CHVE, which hasreactive vinyl ether groups. DMDS, VCH, and IRGACURE 651 were weighedinto a glass jar. The contents were shaken and irradiated for 4 hourswith two GTE 15 watt Sylvania 350 nm black light bulbs having a poweroutput of 1 mW/cm². CHVE and IRGACURE 65 were added to the resultingoligomer, and the solution was irradiated again for 2 hours.

TABLE 3 Total Target DMDS VCH CHVE Initiator M_(N) Oligomer 9 17.12 g5.38 g  9.76 g 0.5% 2800 Oligomer 10 25.09 g 6.05 g 10.98 g 0.6%  830

Oligomers 11 and 12 are described in Table 4 and were prepared with amixture of DMDS and DMDO. The alternative thermal procedure listed abovewas used, and 0.5 percent AIBN was the catalyst level for each reaction.For Oligomer 11, DMDS and DMDO were used in a 70:30 ratio, and forOligomer 12 DMDS and DMDO were used in a 50:50 ratio. For botholigomers, there are more sulfur atoms than oxygen atoms in thebackbone.

TABLE 4 DMDS DMDO CHVE Target M_(N) Oligomer 11  9.00 g  7.62 g 17.08 g2800 Oligomer 12 15.00 g 17.72 g 24.61 g  830

Oligomers 13-18 are described in Table 5 and contain more oxygen atomsthan sulfur atoms in the backbone and were prepared for purposes ofcomparison. The alternative thermal procedure listed above was used, and0.5 percent AIBN was the catalyst level for each reaction.

TABLE 5 DMDS DMDO CHVE PEGDE Target M_(N) Oligomer 13 — 16.00 g 15.01 g— 2800 Oligomer 14 — 15.12 g 10.29 g —  830 Oligomer 15 16.01 g — —22.16 g 2800 Oligomer 16 25.50 g — — 25.53 g  830 Oligomer 17  9.68 g11.49 g — 26.71 g 2800 Oligomer 18 12.51 g 14.78 g — 24.57 g  830

Preparation of DMDT. DMDT, 1,8-dimercapto-3,6-dithiaoctane (Structure9), was prepared from 3,6-dithia-1,8-octadiol using the method of Cooperet al. with the exception that 38 percent HCl was used in place of 48percent HBr in the synthesis. Wolf, R. E., Jr.; Hartman, J. R.; Storey,J. M. E.; Foxman, B. M.; Cooper, S. R. J Am. Chem. Soc. 1987, 109,4328-4335.

EXAMPLES Examples 1-4

Examples 1-4 were prepared by mixing the components in the ratiosidentified in Table 6. The resins were cured by placing 6 grams of theliquid mixture into a 70 mm diameter aluminum dish, heating to 50° C.,and irradiating for 1 hour under two GTE 15 watt Sylvania 350 nm blacklight bulbs having a power output of 1 mW/cm². Clear 1.4 mm thickelastomeric specimens were obtained.

TABLE 6 Example 1 Example 2 Example 3 Example 4 TAIC 5.0 g — 5.0 g — TAC— 5.0 g — 5.0 g DMDS 4.6 g 4.6 g — — HDT — — 4.5 g 4.5 g IGRACURE 0.048g 0.048 g 0.048 g 0.048 g 651

Comparative Examples 1-5

Comparative Examples 1-5 were prepared by mixing the components in theratios identified in Table 7. The resins were cured by placing 6 gramsof the liquid mixture into a 70 mm diameter aluminum dish, heating to50° C., and irradiating for 1 hour under two Sylvania 350 nm black lightbulbs having a power output of 1 mW/cm². Clear 1.4 mm thick elastomericspecimens were obtained.

TABLE 7 Com- Com- Com- Com- Com- parative parative parative parativeparative Example 1 Example 2 Example 3 Example 4 Example 5 TAIC 50 g 5.0g 5.0 g — — TAC — — — 5.0 g 5.0 g DMDO 5.46 g — — 5.46 g — EBMP — 7.14 g— — 7.14 g CAP- — — 16.2 g — — CURE ® 3-800 IRGA- 0.053 g 0.061 g —0.053 g 0.061 g CURE 651

Absorption Performance at 60° C.

The swelling volume of the cured Examples 1-4 and Comparative Examples1-5 were measured. Specimens weighing approximately 0.5 grams were cutfrom the 1.4 mm thick films prepared above, dried for 1 hour in a vacuumoven at a temperature of 100° C. and pressure of 2 torr (266 Pa) andcarefully weighed before immersion in distilled water and in a 96/4mixture, by weight, of water/n-butyl alcohol at 60° C. The samples wereremoved from the liquids carefully patted dry with a paper towel, andweighed after 24 and 72 hours. The percent weight gain was calculated bythe following formula: (swollen weight)-(original weight)/(originalweight). The results of this experiment are reported in Table 8.

TABLE 8 % Weight % Weight % Weight Gain % Weight Gain Gain Gain inWater/n - in Water/n - in Water in Water butanol 96/4 butanol 96/4 (24hr) (72 hr) (24 hr) (72 hr) Example 1 1.0% 1.0% 1.2% 1.4% Example 2 0.8%0.8% 2.42% 3.19% Example 3 0.6% 0.6% 2.1% 2.7% Example 4 0.6% 0.6% 3.42%4.12% Comparative 2.1% 2.1% 6.4% 6.3% Example 1 Comparative 2.9% 3.6%6.2% 7.3% Example 2 Comparative 8.5% 8.0% 22.4% 18.76% Example 3Comparative 1.8% 1.8% 7.7% 7.8% Example 4 Comparative 2.0% 2.4% 8.0%7.8% Example 5

The data in Table 8 clearly show that the ene-thiol resins of Examples 1-4 are much more resistant to swelling in water and in water/n-butanolthan Comparative Examples 1-5. The water/butanol mixture was used tosimulate the swelling characteristics of corrosive inks. The presence ofa nonaqueous component such as butanol significantly increases theswelling of the elastomer network as compared to swelling obtained usingwater alone. Many available inks have significant amounts of watermiscible solvents which typically increase swelling of and, in general,facilitates degradation of the elastomer network.

The absorption data in Table 8 also clearly demonstrates the importanceof maximizing thioether content and minimizing hydrophilic units in thenetwork. The performance of Examples 1 and 2 when compared to that ofComparative Examples 1 and 4 is particularly surprising. Thedimercaptans, DMDO and DMDS, are structurally very similar and thephysical properties of the cured networks before exposure to water werevery similar. However, the resistance to water and water/n-butanol swellof DMDO and DMDS networks is very different.

Absorption Performance at 22° C.

The swelling of Examples 1-4 and Comparative Examples 1-4, was alsomeasured in a 96/4 mixture of water/n-butanol at room temperature (22°C.) and in Lexmark inks. The cyan ink is from Lexmark's colored ink jetcartridge, part number 12A1980. The composite ink is a mixture of cyan,magenta, and yellow inks from Lexmark's colored ink jet cartridge, partnumber 12A1980. The black ink is from Lexmark's black ink jet cartridgepart number 12A 1970. Specimens weighing approximately 0.2 gram were cutfrom the 1.4 mm thick films prepared above, dried for 24 hours at 60° C.in a vacuum oven, and weighed before immersion in the ink orwater/n-butanol solution. The samples swelled in the water/n-butanolmixture or water were immersed at room temperature and removedperiodically, carefully dried with a paper towel, and weighed. Thesamples swelled in the inks were immersed in ink and stored at 60° C.They were periodically removed, and the samples were rinsed with waterto remove the ink. They were patted dry with a paper towel and carefullyweighed. This is the standard swelling procedure used in all examplesand comparative examples. The percentage weight gain was calculated fromthe formula: (swollen weight)-(original weight)/(original weight).Samples soaked in water/n-butanol or water were soaked for a total of 15days. After 15 days, the samples were dried in a vacuum oven at 60° C.for 48 to 96 hours to remove the water and n-butanol from the samples.This dried down weight was recorded and used to report a correctedweight gain for the 15 day swelling studies. The corrected percentageweight gain for the 15 day swelling studies was calculated from thefollowing formula: (swollen weight)-(dried down weight)/(dried downweight). This number is reported to correct for any weight losses in thesamples due to extraction by the water or water/n-butanol mixture of anyuncured material.

The data in Table 9 show the percentage weight increase inwater/n-butanol and ink for the examples and comparative examples. Thedata in Table 9 clearly indicate that Examples 1-4, containing no oxygenether or ester linkages in the dimercaptan backbone, are much moreresistant to swelling in water/n-butanol and ink than the comparativeexamples, which contain ether or ester linkages in the backbone.Dramatic weight losses over several days in ink were observed forComparative Examples 2 and 5, which contain easily hydrolyzed esterfunctional groups.

TABLE 9 % Weight Gain in Water/n-butanol 96/4 Composite Cyan Black (7day/15 day corrected^(a)) (5 day/20 day) (5 day/20 day) (5 day/20 day)Example 1 0.46%/0.60% 1.26%/2.01% 1.23%/1.57% 1.22%/1.34% Example 20.71%/0.99% 1.80%/2.07% 1.77%/1.96% 1.04%/1.30% Example 3 0.64%/0.74%1.52%/2.31% 1.50%/2.10% 1.04%/1.04% Example 4 1.00%/1.35% 2.25%/2.38%1.93%/1.93% 1.00%/1.00% Comparative 3.76%/4.20% 4.65%/5.05% 5.06%/6.35%3.56%/3.55% Example 1 Comparative 5.51%/6.61% 7.33%/1.17%  9.86%/10.32% 7.98%/5.88%^(b) Example 2 Comparative 4.46%/4.86% 4.94%/5.11%5.39%/5.29% 3.38%/3.14% Example 4 Comparative 3.63%/4.41% 6.97%/9.61%6.87%/9.19% 4.93%/0.69% Example 5 ^(a)The samples were dried for 96hours to obtain the corrected weight. ^(b)These numbers represent 2 and5 day data because the sample had disintegrated by 20 days.

Example 5

Samples 1-20 are examples of the invention. These samples exemplify thatene-thiol oligomers containing small amounts of oxygen ether linkagesand large amounts of thioether linkages can be crosslinked to formsolvent, water, and ink resistant elastomeric networks. The samples wereprepared by mixing oligomers with either TAIC or TAC as described in thetable below. The samples were mixed with 0.5 percent IRGACURE 651 andpoured into an aluminum dish or poured into a mold made from two glassplates covered with release liner separated by a {fraction (1/16)} inchsilicone spacer. The samples were irradiated for 1 hour with two GTE 15watt Sylvania 350 nm black light bulbs having a power output of 1mW/cm². The preparation of the samples is described in Table 10.

TABLE 10 Oligomer Cross- Crosslinker Oligomer Weight linker WeightSample 1 Oligomer 1 19.22 g TAC 0.97 g Sample 2 Oligomer 1 17.52 g TAIC0.89 g Sample 3 Oligomer 2 5.21 g TAC 1.00 g Sample 4 Oligomer 2 12.18 gTAIC 2.33 g Sample 5 Oligomer 3 16.30 g TAC 0.99 g Sample 6 Oligomer 315.04 g TAIC 0.94 g Sample 7 Oligomer 4 5.03 g TAC 1.08 g Sample 8Oligomer 4 5.03 g TAIC 1.09 g Sample 9 Oligomer 5 16.53 g TAC 0.88 gSample 10 Oligomer 5 13.92 g TAIC 0.74 g Sample 11 Oligomer 6 5.15 g TAC1.03 g Sample 12 Oligomer 6 13.09 g TAIC 2.61 g Sample 13 Oligomer 715.88 g TAC 0.98 g Sample 14 Oligomer 8 10.17 g TAC 1.51 g Sample 15Oligomer 9 15.97 g TAC 0.91 g Sample 16 Oligomer 10 5.11 g TAC 0.98 gSample 17 Oligomer 10 5.51 g TAIC 1.05 g Sample 18 Oligomer 11 16.13 gTAC 0.87 g Sample 19 Oligomer 12 4.11 g TAC 0.82 g Sample 20 Oligomer 124.07 g TAIC 0.81 g

The ink and moisture resistance for Samples 1-20 is shown in Table 12.The {fraction (1/16)} inch samples were cut into pieces weighingapproximately 0.2 gram, and the standard swelling procedure describedabove was used. Samples 1-20 swelled less than 4 percent in 96/4water/n-butanol at room temperature in 15 days. Additionally, most ofthese samples did not pick up more than 2 percent weight after beingimmersed in water at 60° C. for 15 days. Also remarkable is that each ofthese materials swelled less than 4 percent at 60° C. in each of theinks that were tested. These elastomers have low crosslink densities,either 1000 or 3000 molecular weight between crosslinks. This exampledemonstrates that lightly crosslinked materials in which the number ofthioether groups is maximized and the amount of oxygen ether groups isminimized are resistant to swelling by ink, water, and solvent.

Example 6

Sample 21 was prepared to exemplify that a dimercaptan monomercontaining four sulfurs in the backbone can be used to prepare inkresistant elastomeric networks. It was prepared by mixing DMDT (2.03grams), TAIC (1.57 grams), and IRGACURE 819 (0.018 gram) in an aluminumdish on a hot plate. It was passed through a Fusion processor 10 timesat 20 ft./min. using the Fusion V Bulb.

Sample 21 was tested in water and water/n-butanol using the standardswelling procedure. The water/n-butanol and water resistance of Sample21 is shown in Table 12 and is very similar the data obtained forExample 1 which contains DMDS in its backbone. The equilibriumwater/n-butanol uptake at room temperature is approximately 0.5 percent,and the equilibrium water uptake at 60° C. is approximately 1 percent.Therefore, DMDT, which contains no oxygen ether or ester linkages, is adimercaptan monomer that can be used to make resins that are resistantto swelling in ink, water, or solvent.

Example 7

Samples 22 and 23 are described in Table 11 and exemplify another methodfor synthesizing ink resistant elastomers using ene-thiol chemistry. Inthese samples, a small amount of difunctional olefin monomer, CHVE, wasadded to a difunctional mercaptan and TAIC. These three monomers form alow viscosity solution. The molecular weight between crosslinks can beadjusted by the ratio of CHVE and TAIC. For these samples, a dimercaptanmonomer, CHVE, TAIC, 500 ppm NPAL, and 0.5 percent IRGACURE 651 werecombined and stirred thoroughly. The NPAL was added to prevent prematuregelling of the resin. The liquid was poured into a mold made from twoglass plates covered with release liners and a {fraction (1/16)} inchsilicone spacer. The samples were irradiated for 1 hour with two GTE 15watt Sylvania 350 nm black light bulbs having a power output of 1mW/cm².

TABLE 11 DMDS DMDT CHVE TAIC Sample 22 8.04 g — 3.45 g 5.74 g Sample 23— 9.18 g 2.84 g 4.70 g

Samples 22 and 23 were tested in water/n-butanol and water using thestandard swelling procedure. The swelling of Samples 22 and 23 inwater/n-butanol and water is reported in Table 12 and is also quite low.The equilibrium water/n-butanol uptake is less than 1.5 percent for bothsamples, and the equilibrium moisture uptake is approximately 1 percent.Thus, solvent and moisture resistant resins can be prepared by mixing adimercaptan with a mixture of difunctional and trifunctional olefins andphotochemically curing the resulting solution.

Absorption Performance

Table 12 contains the absorption performance data. The swellingprocedures described above were used. The percentage weight gain in inkwas calculated from the formula: (swollen weight)-(originalweight)/(original weight). The corrected percentage weight gain inwater/n-butanol or water was calculated from the following formula:(swollen weight)-(dried down weight)/(dried down weight). To obtain thedried down weight, Samples 1-20 were dried for 48 hours, and Samples21-23 were dried for 96 hours.

TABLE 12 Water/n-butanol 96/4 Water Composite Cyan Black (7 day/15 daycorrected) (7 day/15 day corrected) (7 day/15 day) (7 day/15 day) (2day/7 day) Sample 1 2.30%/2.08% 0.90%/1.31% 2.52%/2.45% 2.45%/2.38%0.89%/0.71% Sample 2 2.29%/2.07% 0.89%/1.10% 2.26%/2.31% 2.41%/2.58%0.73%/0.58% Sample 3 2.01%/2.35% 0.63%/1.09% 2.43%/2.17% 2.22%/2.53%0.39%/−.13% Sample 4 1.65%/2.26% 0.42%/1.06% 2.10%/2.10% 2.28%/2.55%0.54%/0.54% Sample 5 1.15%/1.87% 0.85%/1.37% 2.81%/2.87% 2.47%/2.41%0.45%/0.57% Sample 6 1.51%/1.93% 0.80%/1.43% 2.62%/2.70% 2.50%/2.43%0.60%/0.40% Sample 7 1.28%/1.73% 0.82%/1.28% 2.27%/2.40% 2.45%/2.67%0.60%/0.12% Sample 8 0.99%/1.37% 0.79%/1.13% 2.26%/2.42% 2.36%/2.52%0.51%/0.00% Sample 9 0.88%/1.17% 1.20%/2.80% 1.97%/1.97% 2.29%/2.40%0.30% Sample 10 0.71%/1.18% 0.52%/0.59% 1.54%/1.39% 1.62%/1.68% 0.42%Sample 11 0.58%/0.95% 0.30%/0.73% 1.16%/1.10% 1.55%/1.69% 0.48%/0.20%Sample 12 0.34%/0.43% 0.14%/0.48% 1.13%/0.92% 1.47%/1.55% 0.43%/0.43%Sample 13 0.57%/0.91% 0.17%/1.38% 0.84%/1.25% 0.85%/0.92% −0.24%/−0.30%Sample 14 0.45%/0.68% 0.11%/1.05% 1.09%/1.03% 0.94%/1.00% 0.32%/0.00%Sample 15 0.76%/1.40% 1.21%/2.94% 1.99%/1.81% 2.20%/2.08% 0.28%/0.14%Sample 16 1.28%/2.14% 0.43%/0.86% 1.27%/1.27% 1.53%/1.70% 0.42%/0.50%Sample 17 0.99%/1.28% 0.41%/0.99% 1.43%/1.24% 1.83%/1.90% 0.54%/0.67%Sample 18 3.70%/3.77% 0.86%/1.19% 3.56%/3.25% 3.29%/3.45% 0.71%/0.65%Sample 19 3.52%/3.84% 0.60%/1.04% 3.14%/3.45% 3.48%/3.48% 1.08%/0.67%Sample 20 3.29%/3.60% 1.03%/1.41% 3.07%/3.36% 3.35%/3.46% 0.91%/0.45%Sample 21 0.49%/0.55% 1.01%/1.24% Sample 22 0.91%/1.18% 0.85%/1.11%Sample 23 1.20%/1.45% 0.76%/0.84%

Comparative Example 6

This comparative example demonstrates that ene-thiol network containingsignificant amounts of oxygen ether linkages have poorer resistance toink, solvent, and water than Samples 1-20. Comparative Samples CS 1-CS10were made by reaction of Oligomers 13-18 with either TAIC or TAC asshown in Table 13. The sample preparation procedure was described inExample 6. The solvent, water, and ink, resistance of the comparativesamples are shown in Table 11. For each of these samples, the swellingin water/n-butanol and ink is higher than that shown in Table 13. Theswelling of samples containing large amounts of oxygen ether linkages isas high as 20 percent in water/n-butanol and 17 percent in ink.

TABLE 13 Oligomer Cross- Crosslinker Oligomer Weight linker Weight CS 1Oligomer 13 11.19 g TAC 0.60 g CS 2 Oligomer 14 4.10 g TAC 0.77 g CS 3Oligomer 14 12.28 g TAIC 2.30 g CS 4 Oligomer 15 14.93 g TAC 0.92 g CS 5Oligomer 16 4.06 g TAC 0.80 g CS 6 Oligomer 16 4.29 g TAIC 0.87 g CS 7Oligomer 17 17.38 g TAC 1.07 g CS 8 Oligomer 17 14.44 g TAIC 0.90 g CS 9Oligomer 18 4.05 g TAC 0.76 g CS 10 Oligomer 18 4.22 g TAIC 0.81 g

Comparative Sample CS 11 demonstrates that an elastomer made from aDMDO, a difunctional olefin, and a trifunctional olefin has poorersolvent and moisture resistance than samples made from dimercaptanscontaining no oxygen ether linkages. Comparative Sample CS 11 wasprepared as described for Samples 22 and 23. DMDO (9.03 grams), CHVE(3.28 grams), and TAIC (5.46 grams) were stirred together 500 ppm NPALand 0.5 percent IRGACURE 651. The liquid was poured into a {fraction(1/16)} inch glass mold and cured. The water/n-butanol and water uptakefor this comparative sample, shown in Table 14, is much higher than wasfound for Samples 22 and 23, which were made from DMDS and DMDT.

Comparative Absorption Data

For the comparative absorption performance data, shown in Table 14, thestandard swelling procedure was used. The percentage weight gain for theinks was calculated from the formula: (swollen weight)-(originalweight)/(original weight). The corrected percentage weight gain inwater/n-butanol or water was calculated from the following formula:(swollen weight)-(dried down weight)/(dried down weight). To obtain thedried down weight, Comparative Samples CS 1-CS 10 were dried for 48hours, and Comparative Sample CS 11 was dried for 96 hours.

TABLE 14 Water/n-butanol 96/4 Water Composite Cyan Black (7 day/15 daycorrected) (7 day/15 day corrected) (7 day/15 day) (7 day/15 day) (2day/7 day) CS 1 6.12%/6.25% 1.33%/1.80% 5.40%/5.29% 5.58%/5.37%1.06%/0.57% CS 2 5.22%/5.22% 1.47%/1.96% 4.79%/4.85% 5.31%/5.47%1.61%/1.54% CS 3 5.05%/5.39% 1.40%/1.88% 5.02%/5.02% 5.52%/5.59%1.98%/1.67% CS 4 11.70%/12.68% 3.75%/5.00% 10.43%/10.71% 10.76%/10.70%5.10%/5.31% CS 5 6.83%/6.04% 2.82%/3.60% 6.17%/6.17% 7.37%/7.14%2.94%/2.76% CS 6 7.12%/7.68% 3.04%/4.20% 6.70%/6.59% 7.37%/7.62%3.56%/3.56% CS 7 18.02%/18.58% 5.83%/7.10% 15.55%/15.49% 16.24%/16.02%9.34%/9.09% CS 8 17.98%/19.62% 5.50%/7.13% 15.67%/15.33% 16.30%/16.30%9.37%/9.37% CS 9 10.56%/11.46% 3.91%/5.11% 10.10%/9.97%  10.88%/11.87%6.69%/5.47% CS 10 11.08%/11.37% 4.07%/5.26% 10.84%/10.84% 11.03%/11.84%5.76%/5.26% CS 11 4.68%/5.15% 1.94%/2.22%

Example 8

Example 8 is a comparison of selected samples having different amountsof sulfur and oxygen present in the network. Example 8 features thewater/n-butanol, water, and cyan ink swelling of selected samplesprepared from oligomers having a theoretical molecular weight of 2800.The molecular weight between crosslinks for these samples isapproximately 3000. The swelling data for the selected samples issummarized in Table 15. Also included in Table 15 is the sulfur weightpercent and oxygen weight percent in the oligomer that was used toprepare in the selected samples. This example demonstrates that as theweight percent of sulfur in the oligomer backbone increases and theweight percent of oxygen in the oligomer decreases, the swellingperformance of the network improves.

TABLE 15 96/4 S weight O weight water/n-butanol swell Water swell Cyanswell % % (7 day/15 day corrected) (7 day/15 day corrected) (7 day/15day) CS 1 18 17 6.12%/6.25% 1.33%/1.80% 5.58%/5.37% Sample 18 26 113.70%/3.77% 0.86%/1.19% 3.29%/3.45% Sample 1 29   8.7 2.30%/2.08%0.90%/1.31% 2.45%/2.38% Sample 15 33  5 0.76%/1.40% 1.21%/2.94%2.20%/2.08% Sample 9 38 0.88%/1.17% 1.20%/2.80% 2.29%/2.40%

Example 9

Example 9 is a comparison of selected samples having different amountsof sulfur and oxygen present in the network. Example 9 features thewater/n-butanol, water, and cyan ink swelling of selected samplesprepared from oligomers having a theoretical molecular weight of 830.The molecular weight between crosslinks for these samples isapproximately 1000. The swelling data for the selected samples issummarized in Table 16. Also included in Table 16 is the sulfur weightpercent and oxygen weight percent in the oligomer that was used toprepare in the selected samples. This example demonstrates that as theweight percent of sulfur in the oligomer backbone increases and theweight percent of oxygen in the oligomer decreases, the swellingperformance of the network improves.

TABLE 16 96/4 S Weight O Weight water/butanol Water Cyan % % (3 day/7day) (3 day/7 day) (2 day/7 day) CS 2 21 17   5.22%/5.22% 1.47%/1.96%5.31%/5.47% Sample 19 28 13   3.52%/3.84% 0.60%/1.04% 3.48%/3.48% Sample3 33 7.4 2.01%/2.35% 0.63%/1.09% 2.22%/2.53% Sample 16 36 4.21.28%/2.14% 0.43%/0.86% 1.53%/1.70% Sample 11 41 0.58%/0.95% 0.30%/0.73%1.55%/1.69%

Example 10

Example 10 demonstrates the low moisture permeability of thioethercontaining networks when compared to similar networks containing oxygenether linkages. In each sample, a difunctional mercaptan was mixed witheither TAIC or TAC, 0.5 percent photoinitiator, and in some cases 500ppm NPAL. The samples were mixed thoroughly at approximately 50° C. andthen degassed in a vacuum oven. Each sample was sandwiched between twoglass plates that had been coated with Teflon tape. The plates wereseparated by spacers that were approximately 4 mils thick. The sampleswere then passed through a Fusion processor at 25 ft/min, five times oneach side. Samples containing IRGACURE 651 as the photoinitiator werecured with the Fusion D bulb, and samples containing IRGACURE 819 as thephotoinitiator were cured with the Fusion V bulb. Samples 24-32 wereprepared in this way and are presented in Table 17.

The permeability test was based on ASTM D814. A “standard” circular die75 mm in diameter was used to punch press specimens from film samplesranging from 80 to 150 microns thick. Release liners were used on bothsides of the specimen to make it easier to handle and measure. This“sandwich” was measured in 10 locations, and the average net filmthickness was recorded.

The specimens were carefully removed from the liners and placed ontofluoroelastomeric gaskets with an outside diameter (O.D.) of 75 mm, aninside diameter (I.D.) of 63.5 mm, and a thickness of 1.5 mm. The gasketand specimen were then placed onto the flanged rim of an aluminumpermeation cup containing 100 mL of deionized water. The cup has avolume of 250 mL. A second gasket, 3 mm thick, was placed over the firstgasket and the specimen, and a 75 mm diameter piece of window screen wasthen placed on top of all three. This screen served to preventstretching of extensible materials.

The gaskets, specimen, and screen were held in place by a circularaluminum ring with an I.D. of 63.5 mm and an O.D. of 88 mm. Along theouter edge of this ring were six evenly distributed threaded holes,through which screws pass into the flanged rim of the cup. The screwswere loosely put in place and the entire assembly placed into a 40° C.oven. After allowing the assembly to equilibrate for 1 hour, the screwswere securely tightened, the cup was removed from the oven, and theinitial weight was taken. Weights were taken every day or so for thefirst week, about every third day the second week, and about every fifthday thereafter.

The permeability (g-mm/m²-day @40° C.), or moisture vapor transmissionrate, was calculated by multiplying the film thickness (mm) by the totalwater weight loss (gram), and dividing by the area of the film (0.003167m²) and the number hours divided by 24 (day). The permeabilities ofSamples 24-32 are shown in Table 17.

TABLE 17 TAIC TAC Dimercaptan Weight (g) (g) Initiator NPAL PermeabilitySample 24 DMDS  5.54 g 5.96 g — 819 Yes  9 Sample 25 DMDS 14.07 g —15.16 g 651 Yes 17 Sample 26 Oligomer 1  8.48 g 0.43 g — 651 No 48Sample 27 Oligomer 2 12.18 g 2.33 g — 651 No 35 Sample 28 Oligomer 4 7.96 g —  1.71 g 651 No 29 Sample 29 Oligomer 4  6.86 g 1.49 g — 651 No24 Sample 30 Oligomer 6 13.09 g 2.61 g — 651 No 18 Sample 31 Oligomer 9 7.25 g 0.42 g — 651 No 35 Sample 32 Oligomer 10  5.09 g 0.98 g — 651 No24

Comparative Example 7

This comparative example demonstrates the higher moisture permeabilityof samples containing significant amounts of oxygen ether linkages whencompared to Samples 24-32. Comparative Samples CS 12-CS 15 were preparedand measured as described in Example 10 and are summarized in Table 18.

TABLE 18 Dimercaptan Weight TAIC TAC NPAL Initiator Permeability CS 12DMDO  5.11 g 4.67 g — yes 651 55 CS 13 DMDO  5.36 g — 4.88 g yes 819 52CS 14 EBMP  6.63 g 4.61 g — yes 651 59 CS 15 Oligomer 14 12.28 g 2.30 g— no 651 99

Example 11

Example 11 is a comparison of samples containing different weightpercentages of sulfur and oxygen in the network but containing the samemolecular weight between crosslinks. Each sample was prepared from anoligomer with a theoretical molecular weight of 830 and TAIC as thecrosslinker. For each sample, the molecular weight between crosslinks isapproximately 1000. This is important because the crosslink density ofthe sample greatly affects the permeability of the sample. The weightpercentages of sulfur and oxygen in the oligomers used to prepare thesamples as well as the moisture permeability are reported in Table 19.The data in Table 19 indicate that the permeability of samplescontaining the same crosslink density varies significantly with theweight percentages of sulfur and oxygen in the backbone. As the weightpercentage of sulfur increase and the weight percentage of oxygendecreases, the permeability of the sample decreases. This exampledemonstrates that the moisture permeability of ene-thiol networks can belowered by maximizing the amount of thioether linkages and minimizingthe amount of oxygen ether linkages in the backbone.

TABLE 19 S Weight % O Weight % Permeability CS 15 21 17 99 Sample 27 337.4 35 Sample 32 36 4.2 24 Sample 30 41 0 18

Example 12

Example 12 demonstrates that the odor of thioether oligomers can bedecreased by the removal of volatile components. An oligomer of DMDS andCHVE having a molecular weight of 1700 was prepared by the thermalprocedure. This oligomer (320 grams) was heated to 80° C. and wasdropped into a UIC rolled film evaporator. The jacket temperature of thecolumn was 100° C., and apparatus was under a vacuum of 0.009 mm Hg. Twocold traps, a cold finger with a temperature of 20° C., and a liquidnitrogen trap to protect the vacuum pump, were used. The rollers wereset at a speed of 300 rpm. Following this treatment of the oligomer, 2.0gram of material were collected in the cold finger, and 3.3 grams ofmaterial were collected in the liquid nitrogen trap. The materialstripped from the oligomer was analyzed and found to contain mostlyresidual monomer and cyclic impurities from the monomer. The odor of theoligomer was significantly reduced. A second treatment of 225 grams ofthe oligomer was carried out with a column temperature of 150° C. Anadditional 0.22 grams of material was collected, and the odor of theoligomer was reduced further.

Other embodiments are within the following claims. While the inventionhas been described with reference to the particular embodiments anddrawings set forth above, the spirit of the invention is not so limitedand is defined by the appended claims.

What is claimed is:
 1. A method of making a ene-thiol elastomercomprising the steps of: (a) providing a composition comprising apolythiol free of hydrophilic groups and having at least two thiolgroups, an aromatic, hetrocyclic, aliphatic, or cycloaliphatic polyenehaving at least two terminal reactive unsaturated carbon to carbonbonds; and (b) exposing the composition to curing energy for asufficient time to form a cured ene-thiol elastomer having a weightincrease of not more than 4 weight percent in 15 days at a temperatureof 22° C. when immersed in a solution of 96 parts by weight water and 4parts by weight n-butanol.
 2. The method of claim 1 wherein an oligomeris formed prior to forming the elastomer.
 3. The method of claim 2further comprising the step of removing residual monomer and impuritiesfrom the oligomer prior to making an elastomer.
 4. A method of making aene-thiol elastomer comprising the steps of: (a) providing a compositioncomprising a mixture of: (1) a thiol terminated oligomer comprising thereaction product of a polythiol having two thiol groups and a firstpolyene or mixture of polyenes having two reactive unsaturated carbon tocarbon bonds wherein not more than 50 weight percent of the polythiolcontains hydrophilic groups and wherein the first polyene comprisesallyl, styryl, cycloalkenyl, 1,4-cyclohexanedimethanol divinyl ether, or(meth)acryl compounds or combinations thereof; and (2) a second polyeneor a mixture of polyenes, having at least 5 percent functionalequivalents of unsaturated carbon to carbon bonds from polyenes havingat least three unsaturated carbon to carbon bonds; and (b) exposing thecomposition to curing energy for a sufficient time to form a curedene-thiol elastomer having a weight increase of not more than 4 weightpercent in 15 days at a temperature of 22° C. when immersed in asolution of 96 parts by weight water and 4 parts by weight n-butanol. 5.The method of claim 4 further comprising the step of removing residualmonomer and impurities from the oligomer prior to making an elastomer.6. The method of claim 4 wherein the first polyene is 4-vinyl-1-cyclohexene; 1,5-cyclooctadiene; diallyl phthalate; or a combinationthereof.
 7. The method of claim 4 wherein the polythiol has the formula:

where m=2-12, n=2-12, q=0-4, where m and n can be the same or different;or the formula H-S-R-S-H, where R=C₅-C₈ cycloaliphatic radical.
 8. Themethod of claim 4 wherein the polythiol is dimercaptodiethyl sulfide;1,6-hexanedithiol; 1,8-dimercapto-3,6-dithiaoctane; or a combinationthereof.
 9. The method of claim 4 further comprising a free radicalinitiator.
 10. The method of claim 9 wherein the free radical initiatoris UV radiation active or thermally active.
 11. The method of claim 1wherein said polyene comprises allyl, vinyl, allyl ether, allyl ester,vinyl ether, styryl, cycloalkenyl, or (meth)acryl compounds, orcombinations thereof.
 12. The method of claim 1 wherein the polyene istriallyl- 1,3,5-triazine-2,4,6-trione; 2,4,6-triallyloxy-1,3,5-triazine;1,4-cyclohexanedimethanol divinyl ether; 4-vinyl-1-cyclohexene;1,5-cyclooctadiene; diallyl phthalate; or a combination thereof.
 13. Themethod of claim 1 wherein the polyene is a mixture of a polyene havingtwo reactive unsaturated carbon to carbon bonds and a polyene havingthree reactive unsaturated carbon to carbon bonds.
 14. The method ofclaim 1 wherein the heterocyclic polyene istriallyl-1,3,5-triazine-2,4,6-trione; 2,4,6-triallyloxy-1,3,5-triazine;or a combination thereof.
 15. The method of claim 1 wherein thepolythiol has the formula:

where m=2-12, n=2-12, q=0-4, where m and n can be the same or different;or the formula H-S-R-S-H, where R=C₅-C₈ cycloaliphatic radical.
 16. Themethod of claim 1 wherein the polythiol is dimercaptodiethyl sulfide;1,6-hexanedithiol; 1,8-dimercapto-3,6-dithiaoctane; or a combinationthereof.